Perforating assembly



Nov. 17, 1959 B. M. CALDWELL 2,912,930

PERFORATING ASSEMBLY Filed Oct. 14, 1955 5L/7ZE M CifiWfd IN VEN TOR.

PERFORATING ASSEMBLY Blake Ml. Caldwell, Fort Worth, Tex., assignor, bymesne assignments, to WeLx, Inc., Fort Worth, Tex., a corporation ofDelaware Application Gctober 14, 1955, Serial No. 540,424 4 Claims. (Cl.1022tl) This invention relates to well perforating assemblies andparticularly to means for providing a blank interval in such assemblies,which blank interval does not include explosive perforating units.

In the completion of wells drilled by the rotary method, it has longbeen the practice to perforate casing set in the well adjacent theproducing formation for the purpose of providing ingress to the wellfrom said formation. Such perforating formerly was done before the wellwas capped and while the heavy drilling mud was within the casing, andafter perforating, the well was completed for production by removing themud, running tubing into the well and capping same. More recently,however, the practice of running in the tubing, affixing the well headequipment, and replacing the drilling mud with clean fiuid, all prior toperforating, has gained considerable popularity in the field, and inthis method the perforating assemblies used must be adapted to belowered through the tubing until, upon emergence therefrom in thevicinity of the oil-bearing formation, the perforating can beaccomplished.

Equipment for perforating wells completed in the aforementioned mannerhas now been devised and a particularly effective type of such apparatusis that wherein the assembly is arranged so that during the lowering ofsame through the tubing the perforating units are in vertical alignmentwith the axis of the tubing, but upon emergence of the assembly from thelower end of the tubing, said units are permitted to pivot to ahorizontal firing position. Such apparatus is disclosed in Patent No.2,543,814 of W. H. Thompson et al., dated March 6, 1951, and entitledMeans and Method of Tilting Explosive Charges in Wells. An improvementupon the Thompson et al. patent, which patent does not provide for aretraction of the apparatus after emergence from the bottom of thetubing, resides in an application for United States Letters Patent,filed February 19, 1954, by Blake M. Caldwell and Joe P. Wier, SerialNumber 411,349, entitled Tilting Charge Well Perforating Assembly. Afurther improvement upon such apparatus resides in an application forUnited States Letters Patent, filed October 8, 1954, by Blake M,Caldwell and Harrold D. Owen, Serial Number 461,236, entitled WellPerforating Assembly.

In such apparatus there is provided a firing head from which issuspended an elongated carrier, pivotally carrying shaped charges, theshaped charges being resiliently urged to horizontal position, but byinterlock means normally being held in axial disposition with respect tothe carrier. An explosive release means, such as a squib, abuts a detenton the bottom shaped charge and upon firing of the squib the bottomshaped charge is permitted to pivot to horizontal position, releasingthe others so that they too may assume horizontal, or firing, position.Control means are provided in such apparatus whereby the shaped chargesmay not be fired in the event they are prevented as by well obstructionsfrom attaining the described firing position.

Patented Nov. 17, 1959 The instant invention is concerned particularlywith interconnecting means between the shaped charges suspended in thecarrier. As previously stated, the charges in the aforementionedapparatus are interlocked the Quote the other and when the charges arepivoted to firing position and fired, a regular pattern of perforationsis produced in casing and formation. This uniform spacing ofperforations is normally desired but, frequently, it is necessary thatan entire zone or zones of the formation not be perforated as, forexample, where there is a shale streak at a given level or a piece ofapparatus in the well which is not to be perforated.

It is, therefore, the object of this invention to provide explosiveshaped charge apparatus of the characterabove described wherein groupsof charges may be longitudinally spaced from each other, such spacing tobe in such extent as to suit the exigencies of the particular job athand.

In the accompanying drawings:

Figure 1 shows a side elevational view of a perforating assemblyconstructed in accordance with the invention set forth in theaforementioned application, Serial Number 461,236;

Figure 2 shows a partial side elevational view of the foregoingapparatus incorporating, however, the instant invention; and

Figure 3 shows the apparatus incorporating the invention after therelease of the charges and the pivoting thereof to firing disposition.

In its general aspect, the invention comprises a firing head 10'supported by a conductor cable, not shown, which is suspended in thewell from the surface. Carried by the firing head 10 is an elongatedcarrier 14 through which passes a detonating fuse 16, detonated by thefiring head. Said detonating fuse passes adjacent shaped charges 18,which charges are pivotally mounted within the carrier and areresiliently urged to horizontal position, being fired by the detonatingfuses. Said charges are, however, by means such as the detents 20 heldinterlocked in axial disposition with respect to the carrier. A releasemeans which could be solenoid or other electrically operated stop means,but which is shown here as the explosive cartridge, or squib 22, iselectrically connected through a suitable conductor 24 to the firinghead 10 and abuts the detent Zfia of the bottom shaped charge. Uponfiring of the squib, the bottom shaped charge is permitted toresiliently pivot to horizontal position. Pivoting of the bottom shapedcharge releases the next shaped charge for similar resilient pivotalmovement to horizontal position, and the process is repeated to permiteach charge to assume firing disposition.

Electrical control means, not shown, are provided whereby the shapedcharges may not be fired from the surface in the event they areprevented, as by well obstructions, from reaching a proper firingposition. These control means are actuated by a plunger 30 connected toan upper release arm 32, which itself is provided with one of thedetents 2t), for interlock with the uppermost shaped charge. Thus, uponfiring of the squib and horizontal pivoting of the shaped charges, therelease arm 32 is likewise pivoted urging the plunger Stl upward topermit firing of the shaped charges.

it is with the interlocking and plunger operating characteristics of theinstant assembly that this invention is particularly concerned and, inessence, said invention resides in the arrangement whereby a blankinterval is provided in the carrier, which interval is bridged by anelongated rod, which rod operates to release the upper shaped chargesfrom interlock in response to the release of the lower shaped chargesupon firing of the squib 22.

Detailed description of the general perforating assembly is set forth inthe aforesaid application, Serial Number 461,236, and it is believedthat the general description of said assembly set forth above sufficiesbut for the means establishing the blank interval. In this regard, andat a position within the assembly where a blank interval is desired, atandem release arm 34 is pivotally afiixed to the carrier 14, whichtandem release arm is adapted to pivot outwardly and upwardly as do thecharges 18 under the urging of a resilient spring 36. An extension 38 ofthe release arm is adapted to interlock with the detent 20 of the nextadjacent shaped charge 18 whereby, upon pivoting of the release arm, theshaped charge is, in turn, permitted to pivot and the assembly tooperate in the manner previously described.

Pivotally affixed to the tandem release arm 34 is a clevis 40 into whichis threaded a connecting rod 42, which connecting rod may be varied asto desired length through provision of the threaded collars 44. A clevis46 is pivoted to a lower release arm 48 which, in turn, is pivoted tothe carrier 14 and pivotally urged by the resilient spring 50 towardshorizontal position. As with the tandem release arm, the lower releasearm 48 is provided with an extension 52 which interlocks with the detent20 of the lower adjacent shaped charge. If desired, the detonating fuse16 and conductor 24 may be wrapped about the rod 42 as shown on Figures2 and 3 to stabilize their positioning and prevent damage as by scrapingagainst the casing or well wall.

Thus, it may be seen that through the instant inven- By these means isprevented the necessity, for example,

of more than one run into the hole when spaced zones of a formation mustbe perforated. Similarly, the invention avoids the well-knowndifficulties attendant upon the design and operation of apparatussuitable for firing a number of charges of a perforating assembly,moving the said assembly and firing other charges.

While there has been described what is at present considered a preferredembodiment of the present invention, it will be apparent to thoseskilled in the art that various modifications and chanegs may be madewithout departing from the essence of the invention, and particularlythat the invention herein presented is adapted to various types andkinds of tools other than well perforating assemblies. It is intended tocover herein all such modifications and changes as come within the truescope and spirit of the appended claims.

I claim:

1. A well perforating assembly comprising: an elongated carrier; meansfor lowering said carrier into a well; an upper and a lower group ofshaped charges pivotally mounted on said carrier, the shaped charges ofeach said group being interlocked in axial disposition with respect tosaid carrier; bridging means between said groups, said bridging meansincluding an elongated rod and release arms connected thereto andpivotally mounted on said carrier, said release arm interlocking thelowermost shaped charge of said upper shaped charge group and theuppermost shaped charge of said lower shaped charge group; resilientmeans urging said shaped charges and said release arms to pivot fromsaid axial disposition; release means maintaining said shaped chargesand said release arms so interlocked, said release means including aconductor; a detonating fuse for firing said shaped charges; and meansoperable from the surface of said well for operating said release meansto release said shaped charges and said release arms from interlock to V4 permit pivotal movement from such axial disposition and for firingsaid detonating fuse.

2. A well perforating assembly comprising: an elongated carrier; meansfor lowering said carrier into a well; an upper and a lower group ofshaped charges pivotally mounted on said carrier, the shaped charges ofeach said group being interlocked in axial disposition with respect tosaid carrier; bridging means between said groups, said bridging meansincluding an elongated rod and release arms connected thereto andpivotally mounted on said carrier, said release arms interlocking thelowermost shaped charge. of said upper shaped charge group and theuppermost shaped charge of said lower shaped charge group; resilientmeans urging said shaped charges and said release arms to pivot fromsaid axial disposition; release means maintaining said shaped chargesand said release arms so interlocked, said release means including aconductor; a detonating fuse for firing said shaped charges; and meansoperable from the surface of said well for operating said release meansto release said shaped charges and said release arms from interlock topermit pivotal movement from such axial disposition and for firing saiddetonating fuse, said conductor and said detonating fuse being wrappedabout said elongated rod.

3. A bridging device for a well perforating assembly comprising: anelongated carrier member; an upper release arm pivotally mounted on saidcarrier member for movement between a position longitudinal and aposition transverse of said carrier; a lower release arm pivotallymounted on said carrier member for movement between a positionlongitudinal and a position transverse of said carrier member; aconnecting rod having its ends pivoted to said release arms on oppositesides of the pivot points of said release arms; resilient means urgingsaid release arms to pivot from said longitudinal position to saidtransverse position; a lower shaped charge pivotally mounted on saidcarrier below said lower release arm; an upper shaped charge pivotallymounted on said carrier above said upper release arm; said shapedcharges being longitudinally aligned with respect to the carrier andpivotable to positions transverse to the carrier; resilient means urgingsaid shaped charges to pivot from said longitudinally aligned positionsto said transverse positions; interlocking detents on said lower releasearm and said lower shaped charge restraining said lower release arm insaid longitudinal position, said detents disengaging upon pivoting ofsaid shaped charge to release said lower arm for pivotal movement; andinterlocking detents on said upper release arm and said upper shapedcharge restraining said upper shaped charge in said longitudinallyaligned position, said detents disengaging upon pivoting of said upperrelease arm to release said upper shaped charge for pivotal movement.

4; A bridging device for a well perforating assembly comprising: anelongated carrier member; an upper release arm pivotally mounted on saidcarrier member for movement between a position longitudinal and aposition transverse of said carrier; a lower release arm pivotallymounted on said carrier member for movement between a positionlongitudinal and a position transverse of said carrier member; aconnecting rod having its ends pivoted to said release arms at the sidesof the pivot points of said release arms; resilient means urging saidrelease arms to pivot from said longitudinal. position to saidtransverse position; a lower shapedcharge pivotally mounted on saidcarrier below said lower release arm; an upper shaped charge pivotallymounted on said carrier abovesaid upper release arm; said shaped chargesbeing longitudinally aligned with respect to thecarrier'and pivotable topositions transverse to the carrier; resilient means urging said shapedcharges to pivot from said longitudinally aligned positions to saidtransverse positions; interlocking detents on said lower release arm andsaid lower shaped charge restraining said lower release arm in saidlongitudinal po- References Cited in the file of this patent UNITEDSTATES PATENTS Kanady July 7, 1953 McKean Dec. 29, 1953 FOREIGN PATENTSFrance Mar. 11, 1953

